Pneumatic suction device, pneumatic sanding system implementing such a device and corresponding facility

ABSTRACT

A pneumatic suction device including a suction nozzle connected to a suction unit and at least one air amplification module located in at least one hose for connecting said suction nozzle to the suction unit. The at least one air amplification module includes at least two air amplifiers operating according to a Coanda effect.

FIELD OF THE INVENTION

The technical field is that of pneumatic suction, and in particular dust suction, devices. Such suction devices may be implemented to suck in dusts created by the operation of a tool, such as a pneumatic sander or grinder for example.

More particularly, the invention relates to suction amplification means intended to be implemented in such a pneumatic suction device.

PRIOR ART

In the car body repair field, the sanding/grinding operation is combined with the use of a suction device to collect the sanding particles, in particular aluminium particles, also called hereinafter dust. When sucked in, the particles do not pollute ambient air in the garage and this protects air surrounding the car-body mechanic.

Once stored, the aluminium dust can explode in the presence of a spark (from an electric motor, for example). Thus, the sanders and the suction devices used by car-body mechanics should comply with the ATEX standard. This standard is intended for risky environments and for sanding specific materials.

For occasional uses or for areas that are hard to access, complete mobile sets are known composed by a suction unit (a wheeled suction device, for example) and an electric sander.

In order to comply with the ATEX standard, the electrical portions of electrical sanders used in these mobile sets must be isolated from the outside and from the sucked dust in particular. Such insulation is relatively complex and expensive to implement. Thus, the cost of these sanders is very high, which forms a major obstacle to use thereof in a large scale. In addition, in car body workshops, the mobile sanding equipment is barely maintained. Hence, the fine particles clog the collection bag and the possible filters, which results in suction being quickly altered. Furthermore, the weight of the electrical sander is relatively high, which affects its ergonomics.

Thus, in general, car-body mechanics use pneumatic sanders since these are light, handy and have no risk in the presence of aluminium particles. In general, pneumatic sanders are connected to a suction unit, itself connected to a compressed air network deployed in the premises of the car-body mechanic. Thus, both of the pneumatic sander and the suction device are connected to the compressed air network of the premises of the car-body mechanic.

A drawback of this solution lies in the fact that to obtain an optimum operation of the pneumatic sander and suction device, it is necessary to provide an air supply at a very high pressure, in the range of about 7 bars. Yet, all premises provided with a compressed air supply network are not necessarily capable of supplying such an air pressure.

In addition, this very high air consumption of the sander and of the suction device can generate disturbances throughout the entire compressed air network. In particular, this might cause air flow rate variations on the other tools of the facility and cause quality problems, for example in the case of a pneumatic painting station.

Indeed, the pneumatic suction devices generally implement a Venturi effect type air suction. A Venturi effect air suction is well known since it is widely used in the industry for the vacuum creation on grippers with chucks. Since the depression of the chucks does not generate a significant air flow rate, its use is therefore relatively economic.

Nonetheless, when such a solution is implemented in pneumatic suction devices, it is necessary to use large-sized Venturi effect modules so that the generated depression and the suction flow rate are enough to suck in dust. Hence, the orifice of the nozzle of the Venturi effect module is oversized in order to recover a high air flow rate. Hence, the air consumption is very high. For example, when testing such a solution, the Applicant has observed a significant drop in the air pressure in the compressed air network supplying the entire workshop, the air pressure at the inlet falling from 7 bars to 3 bars. This results in a much lower air flow rate for the sander and an alteration of the general compressed air network of the workshop.

In other words, this solution is not satisfactory since it has a high air consumption for non-optimum suction performances.

In turn, the document FR1191387 describes a solution implementing a Coanda effect type amplifier, but in the oil extraction field.

Hence, there is a need for providing a new suction solution which allows obtaining an optimum operation of the suction device when it is used with a pneumatic sander on a compressed air supply network offering a lower air pressure than the prior art, for example in the range of 5 bars.

This solution should also provide high suction performances while allowing for an optimum intake air consumption, in order not to disturb the compressed air supply network of the workshop.

SUMMARY OF THE INVENTION

The technique of the invention allows solving at least some of the drawbacks raised by the prior art. More specifically, the invention relates to a pneumatic suction device comprising a suction nozzle connected to a suction unit and at least one air amplification module located in at least one hose for connecting said suction nozzle to said suction unit.

According to the invention, said at least one air amplification module comprises at least two air amplifiers operating according to Coanda effect.

The implementation of an air amplification module comprising at least two air amplifiers according to the invention allows providing optimum suction performances, to the extent that the depression created by the air amplifiers is high while maintaining controlled air consumption.

In particular, these optimum performances are obtained by the implementation of a suction device operating only pneumatically and comprising air amplifiers operating according to Coanda effect.

Thus, the invention allows providing a suction solution particularly suited to dust, and in particular aluminium dust, suction. Furthermore, the pneumatic suction device according to the invention is compliant with the standard ATEX, a standard that should be complied with in car body workshops.

Thus, the invention suggests a new and inventive approach allowing solving the drawbacks of the prior art by providing a suction solution that is simple to implement offering high suction performances or optimum air consumption. Thus, the invention provides a new suction solution which has superior performances than the previously-described suction solutions of the prior art.

According to a particular aspect of the invention, said at least two air amplifiers are disposed in parallel within said at least one amplification module.

The particular arrangement of the air amplifiers in parallel in the amplification module allows simplifying the air flows in the connecting hoses. In addition, this arrangement of the amplifiers within the amplification module allows significantly limiting turbulences at the inlet and at the outlet of the amplification module, so as to further simplify the air flows and limit depression and air flow rate losses, in particular.

According to another particular aspect of the invention, said at least one amplification module comprises a base having at least two first bores, called air inlet bores, extending through said base.

According to still another particular aspect of the invention, said at least one amplification module comprises a body in which said at least two air amplifiers are formed at least in part, said body comprising for each of said at least two air amplifiers:

-   -   a second bore, called air outlet bore, substantially circular or         conical, extending from a first side of said body oriented         towards said suction nozzle;     -   a fillet, extending said outlet bore and making junction between         walls of said outlet bore and a surface opposite to said first         side of said body.

Said at least one amplification module comprises, for each of said at least two air amplifiers, a slot adjacent to said fillet, said slot being configured to enable an additional air inlet in said air amplifier.

The particular implementation of the inlet bore, of the outlet bore, of the fillet and of the slot allows obtaining optimum performances, in particular thanks to the Coanda effect generated in the air amplifiers.

According to a particular aspect of the invention, said slot is configured to enable a compressed/pressurised air intake.

The implementation of this slot allows making a pressurised air flow enter, entering at a higher velocity in the air amplification module than the air flow sucked in into the latter, so as to obtain Coanda effect.

According to another particular aspect of the invention, said slot is in fluidic communication, on the one hand with said first bore and/or said fillet and, on the other hand with a pressurised air chamber.

Thus, the air amplification module features a simple solution to introduce pressurised air into the air amplifiers.

According to a particular aspect of the invention, said slot has a width comprised between 0.05 and 0.1 mm.

According to another particular aspect of the invention, said fillet has an opening comprised between 1 and 5 mm.

The invention also relates to a sanding/grinding system, in particular for a car body workshop, comprising a pneumatic sander/grinder connected to a pneumatic suction device as described before.

The low air consumption of the pneumatic suction device according to the invention allows guaranteeing an optimum operation of the sander and of the other pneumatic tools/devices connected on the general compressed air supply network of the workshop. Thus, the disturbances generated on the general compressed air supply network of the workshop by the operation of the dust suction device are limited, and even suppressed.

The invention also relates to a facility comprising a general compressed air supply network comprising at least one sanding system as described before.

LIST OF THE FIGURES

The invention, as well as the different advantages thereof, will be understood more easily, in light of the following description of an illustrative and non-limiting embodiment thereof, and from the appended drawings wherein:

FIG. 1 schematically illustrates a pneumatic suction device implementing a suction amplification module according to an embodiment of the invention;

FIG. 2 is a sectional view of a suction amplification module according to an embodiment of the invention;

FIG. 3 is a detailed sectional view of an air amplifier implemented in the amplification module of FIG. 2 ;

FIG. 4 is a detail view of a portion of the air amplifier of FIG. 3 ; and

FIG. 5 schematically illustrates a sanding system for a car body workshop comprising a pneumatic suction device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The general principle of the invention is based on the implementation of at least one air amplification module 2 within a dust pneumatic suction device 1, for example in a car body workshop.

Such a device 1, illustrated in FIG. 1 , comprises a suction unit 10 supplied with pressurised air, or with compressed air, by air supply hoses 14 connected to a general compressed air supply network 8 of the workshop in which the suction device 1 is used.

The suction unit 10 is connected to a suction nozzle 12 via suction hoses, or connection, hoses 13.

The suction device 1 comprises at least one air amplification module 2 (one single module in the example illustrated in FIG. 1 ), positioned/located between the suction unit 10 and the suction nozzle 12. The amplification module 2 is disposed in the suction hose 13 such that all of the inlet air flow sucked in by the suction nozzle 12 crosses/passes through the air amplification module 2 up to the suction unit 10. Preferably, the air amplifier module 2 is located proximate to the suction nozzle 12.

In one variant, it could be considered to implement a plurality of air amplification modules 2 between the suction unit 10 and the suction nozzle 12. In this case, the air amplification modules 2 are dispose in series and are, for example, spaced apart evenly from one another in the suction hoses 13.

According to the invention, each air amplification module 2 comprises at least two air amplifiers 21 operating according to Coanda effect. According to the studies performed in the field, an air amplifier 21 operating according to the Coanda effect allows, when used in air suction, multiplying by three the suction flow rate at the outlet of the air amplifier.

Preferably, the air amplifiers 21 are disposed in parallel in the air amplification module 2, i.e. the inlet air flow in the air amplification module 2 is split in two to cross the air amplifiers 21. In other words, a portion of the inlet air flow crosses one of the amplifiers 21 whereas another portion of the inlet air flow crosses the other amplifier 21.

The particular arrangement of the air amplifiers 21 in parallel in the amplification module 2 allows simplifying the air flows in the suction hoses 13. In addition, this arrangement of the air amplifiers 21 within the amplification module 2 allows significantly limiting turbulences at the inlet and at the outlet of the amplification module 2, so as to further simplify the flows and limit the depression and/or air flow rate losses, in particular.

In this example, splitting of the air flow is equal/balanced. In other words, the inlet air flow crossing each amplifier is equal, i.e. half of the inlet air flow crosses one of the amplifiers 21 whereas the second half of the inlet air flow crosses the other amplifier 21. It may also be considered to split the inlet air flow into unequal portions.

Splitting of the inlet air flow in the air amplification module 2 depends on the structure of the base 20 (described hereinbelow) of the air amplification module 2. Indeed, it is possible to manufacture/machine the base 20 to split the inlet air flow as desired.

The type of the air amplifier (herein a Coanda effect one) as well as the particular arrangement of the air amplifiers 21 within the air amplification module 2 (herein in parallel) allows obtaining a suction device 1 that maintains a high air flow rate while preserving an optimum depression. Thus, the air flow rate of the suction device 1 according to the invention allows promoting suction of dust at the nozzle 12, which may for example be in the form of holes formed at the tray of a pneumatic sander (not represented). In addition, the depression provided by the suction device 1 according to the invention allows sucking in dust in an optimum manner (irrespective of their dimensions) and bringing/conveying them efficiently up to the dust recovery/storage means.

It should be noted that, when used conventionally, Coanda effect amplifiers supply a low air flow rate for a high depression. In addition, they have the drawback of seeing the depression drop progressively as the air flow rate increases. Hence, a Coanda effect air amplifier was not obviously intended to be implemented in a dust suction device, which requires high air flow rate and depression. Hence, it is actually the implementation of at least two Coanda effect air amplifiers in parallel that allows obtaining unexpected performances compatible with a use in a suction system.

Thus, the suction device 1 according to the invention provides a solution having low air consumption at the inlet, a good suction flow rate and a good depression.

The dimensions of the air amplifiers 21 may be selected according to the application, the constraints of the system or of the workshop and the desires of the user in terms of air flow rate, depression and air consumption at the inlet.

FIG. 2 illustrates in sectional isolated view an air amplification module 2 according to the invention.

The air amplification module 2 comprises a base 20, for example made of a metallic or plastic material. The base 20 may be machined/formed, at a first end, so as to have a receptacle 201 for connection with a suction hose 13. The connection receptacle 201 is located on the side of the air amplification module 2 oriented towards the suction nozzle 12 of the device 1.

An external surface 202 of the base 20, located proximate to the second end of the air amplification module 2, can be configured to enable connection with another suction hose 13, this other suction hose 13 being that one located/oriented on the side of the suction unit 10 of the suction device 1.

In one variant, the air amplification module 2 can be integrated or fitted into a suction hose 13. Hence, the connection receptacle 201 as well as the external surface 202 can then be adapted/modified.

The base 20 comprises a main air inlet 203 that then splits into two inlet bores 204. The inlet bores, or first bores, 204 are substantially circular or conical shaped. The inlet bores 204 split the intake air flow into the air amplification module 2 in two portions and direct each of the portions of the intake air flow towards the air amplifiers 21.

The base 20 of the air amplification module 2 also comprises a pressure chamber 205 formed proximate to each inlet bore 204. In this example, two circular pressure chambers 205 are implemented proximate to each inlet bore 204, preferably on each side of the latter.

The base 20 is configured to cooperate with a body 210 carrying air amplifiers 21. More specifically, the base 20 and the body 210 are configured such that each of the air amplifiers 21 is located opposite an air inlet bore 204.

The air amplifiers 21 and the inlet bores 204 are in fluidic communication in order to enable the sucked air, i.e. the air taken in into the air amplification module 2, to cross the inlet bore 204 then the air amplifier 21, without any air loss. In other words, the air amplifiers 21 are placed/fastened in the air amplification module 2 in an airtight manner in their respective receiving receptacle.

In the example illustrated in FIG. 2 , the air amplifiers 21 being identical, they are therefore described only once. It should be understood that the air amplifiers 21 implemented in an air amplification module 2 of the invention are identical, or at least in their structure and their operation. Nonetheless, according to non-illustrated variants, they may have different dimensions.

The air amplifiers 21 are machined/formed in a body 210. The body 210 comprises, for each air amplifier 21, a second bore, called outlet bore, 212 located at a first end 215 of the air amplifier 21, i.e. at the end oriented on the side of the air outlet of the air amplifier module 2, in other words on the side of the suction unit 10 of the suction device 1. The air outlet bores 212 are substantially circular or conical. The outlet bore 212 extends substantially throughout the entire body 210, i.e. from one end to another.

FIG. 3 illustrates in more details an air amplifier 21 within the air amplification module 2.

As illustrated, the outlet bore 212 is extended by a fillet 213 which connects the surface of the outlet bore 212 with the lower surface 216 of the air amplifier 21, i.e. the surface of the air amplifier 21 located on the side of the air inlet in the air amplifier 21.

The fillet 213 is configured to cause/form a constriction of the air passage orifice between the inlet bore 204 of the amplification module 2 and the outlet bore 212 of the air amplifier 21 in order to obtain the desired Coanda effect.

The fillet 213 has a large radius and is selected so as to optimise the performance of the Coanda effect. The fillet 213 further has an opening, or thickness, e1 (represented in FIG. 4 ) comprised, for example, between about 1 and 5 mm, depending on the dimensions of the air amplifier 21 and the desired performances.

For example, the fillet 213 preferably has a 3 mm opening e1.

A slot 214, formed at the junction between the base 20 of the amplification module 2 and the body 210 of the amplifier, connects at least one pressure chamber 205 with the inlet bore 204. In other words, the slot 214 forms a complementary/additional air inlet in the air amplifier 21. This additional air inlet is positioned substantially perpendicularly to the longitudinal axis of the inlet 204 and outlet 212 bores.

More specifically, the slot 214 is adjacent to the fillet 213 of the air amplifier 21. The geometry of the slot 214 is selected so as to optimise the performance of the Coanda effect. For example, the slot 214 has a width, or a thickness, e2 (represented in FIG. 4 ) comprised between about 0.05 and 0.1 mm, depending on the dimensions of the air amplifier 21 and the desired performances.

For example, the slot 214 preferably has a 0.07 mm width e2.

Hence, the slot 214 allows making compressed air, i.e. pressurised air, enter at the level of the fillet 213, between the inlet 204 and outlet 212 bores, so as to obtain the desired wall effect (i.e. Coanda effect).

Hence, the Coanda effect obtained within the air amplifier 21 allows accelerating air in the air amplifier 21. Thus, the depression as well as the air flow rate are simply increased. Hence, the implementation of two air amplifiers 21 as described hereinabove allows improving the suction performances of the suction device 1.

The air flows within the air amplification module 2 are schematically illustrated in FIGS. 2 to 5 .

Air sucked in by the suction nozzle 12 is conveyed up to the amplification module 2 through the suction hoses 13 (as illustrated in FIG. 1 ). Air sucked in by the suction nozzle 12 forms an inlet air flow 31. The inlet air flow in an air amplifier 21 may form only a portion of the overall inlet air flow 31 entering the amplification module 2, since the amplification module 2 includes at least two air amplifiers 21 dispose in parallel, as described before.

The pressure chamber 205 is connected to the general compressed air supply network 8 (illustrated in FIG. 1 ) and supplies, via the slot 214, and additional pressurised inlet air flow 32 at the junction between the inlet bore 204 and the fillet 213.

At the outlet of the air amplifier 21, i.e. at the outlet bore 212, the outlet flow 33 therefore consists of the sum of the inlet flow 31 and of the additional pressurised inlet air flow 32. The velocity of the outlet flow 33 is higher than the inlet velocity of the inlet flow 31 thanks to the constriction formed by the fillet 213 and to the additional pressurised air inlet 32.

It should be noticed in the FIGS. 3 and 4 that the additional pressurised inlet air flow 32 introduced by the slot 214, between the inlet bore 204 and the fillet 213, creates an acceleration and a “pressing” of the air flow against the wall of the outlet bore 212. The air flow represented by the arrow 321 almost sticks to the wall of the outlet bore 212, also resulting in induced air flows (not represented) which therefore accelerate all of the outlet flow 33 at the outlet of the air amplifier 21.

In other words, air sent under pressure via the slot 214 remains proximate to the walls of the outlet bore 212. Hence, the air velocity over the walls of the outlet bore 212 sucks in by entrainment air at the centre of the outlet bore 212, as illustrated by the arrows 331.

The inlet 31 and outlet 32 air flows convey the dust sucked in at the suction nozzle 12. The acceleration of the flows provided by the air amplifiers 21 allows conveying the dust effectively from the suction nozzle 12 up to the suction unit 10, without any suction loss.

The air amplifiers 21 also allow providing a sufficient depression and an optimum air flow rate to move/convey aluminium dust, in particular when such a suction device is implemented with a pneumatic sander in a car body workshop.

Other Aspects and Variants of the Invention

In FIGS. 2 to 4 , the inlet bore 204 of the amplification module 2 comprises a circular-shaped unique portion. In a non-illustrated variant, the inlet bore 204 of the amplification module 2 may comprise a first conical-shaped portion extended by a second circular-shaped portion. It should be understood that the opposite could also be considered. Other variants, i.e. in terms of number of portions and of shape may be considered without departing from the general principle of the invention.

The same applies for the outlet bore 212 of the air amplifier 21. In the illustrated example, it has a conical-shaped unique portion. Other variants, i.e. in terms of number of portions and of shape may be considered without departing from the general principle of the invention.

In a non-illustrated variant, the air amplifiers may be manufactured in the same part integrating both inlet and outlet bores and cooperating with the base. The base of the amplification module is then adapted to receive the amplifiers and direct the air inlet flow towards each of the air amplifiers.

In another variant, the air amplification module is machined so as to directly integrate the air amplifiers. In other words, the base and the body are manufactured in the same single part. In other words, the air amplification module is made in one-piece.

In still another variant, the air amplification module is manufactured into several parts assembled together so as to form the inlet and outlet bores, the fillet and the slot.

Each air amplifier 21 may be fluidly connected to one or two pressure chamber(s) 205 supplied with pressurised air, as illustrated in FIGS. 2 to 4 .

FIG. 5 schematically illustrates a sanding system 9 for a car body workshop comprising a pneumatic sander 91 connected to a pneumatic suction device 1 as described before, the sander 91 and the suction device 1 being connected to the general compressed air supply network 8

The pneumatic suction device 1 allows obtaining high suction performances yet without having considerable air consumption on the general compressed air supply network 8. Thus, the other pneumatic tools/devices used on the network 8 of the workshop are not disturbed by the operation of the sanding system 9.

In the context of the development of the pneumatic suction device of the invention, the Applicant has tested and compared suction devices of the prior art. In particular, the Applicant has been able to test and compare the suction device of the invention with a pneumatic suction device operating with a Venturi effect type amplifier and with an electrical suction device.

These tests have allowed revealing that the suction device according to the invention allowed obtaining suction performances at least as high as with the suction devices of the prior art. Yet above all, these tests have shown that the suction device according to the invention consumes a substantially smaller amount of air at the inlet, to achieve the same suction performances. 

1. A pneumatic suction device comprising: a suction unit; a suction nozzle connected to the suction unit; and at least one air amplification module located in at least one hose for connecting said suction nozzle to said suction unit, wherein said at least one air amplification module comprises at least two air amplifiers operating according to a Coanda effect, said at least two air amplifiers being disposed in parallel within said at least one amplification module.
 2. The pneumatic suction device according to claim 1, wherein said at least one amplification module comprises a base having at least two first bores, called air inlet bores, extending through said base.
 3. The pneumatic suction device according to claim 2, wherein said at least one amplification module comprises a body in which said at least two air amplifiers are formed at least in part, said body comprising for each of said at least two air amplifiers: a second bore, called air outlet bore, substantially circular or conical, extending from a first side of said body oriented towards said suction nozzle; a fillet, extending said outlet bore and making junction between walls of said outlet bore and a surface opposite to said first side of said body; said at least one amplification module comprising, for each of said at least two air amplifiers, a slot adjacent to said fillet, said slot being configured to enable an additional air intake in said air amplifier.
 4. The pneumatic suction device according to claim 3, wherein said slot is configured to enable a compressed/pressurised air intake.
 5. The pneumatic suction device according to claim 3, wherein said slot is in fluid communication with said first bore and/or said fillet and with a pressurised air chamber.
 6. The pneumatic suction device according to claim 3, wherein said slot has a width comprised between 0.05 millimeters (mm) and 0.1 mm.
 7. The pneumatic suction device according to claim 3, wherein said fillet has an opening comprised between 1 millimeter (mm) and 5 mm.
 8. A sanding system for a car body workshop, comprising: a pneumatic suction device comprising: a suction unit; a suction nozzle connected to the suction unit; and at least one air amplification module located in at least one hose for connecting said suction nozzle to said suction unit, wherein said at least one air amplification module comprises at least two air amplifiers operating according to a Coanda effect, said at least two air amplifiers being disposed in parallel within said at least one amplification module; and a pneumatic sander connected to the pneumatic suction device.
 9. A facility comprising: a general compressed air supply network; and at least one sanding system connected to the general compressed air supply network and comprising: a pneumatic suction device comprising: a suction unit; a suction nozzle connected to the suction unit; and at least one air amplification module located in at least one hose for connecting said suction nozzle to said suction unit, wherein said at least one air amplification module comprises at least two air amplifiers operating according to a Coanda effect, said at least two air amplifiers being disposed in parallel within said at least one amplification module; and a pneumatic sander connected to the pneumatic suction device. 